1. Field of the Invention
The present invention relates to a gas charging apparatus for charging a gas into a container such as a carrier cassette for storing semiconductor wafer substrates or glass substrates in the fabrication of semiconductor devices or any other devices using glass substrates, a gas discharging apparatus for discharging a gas from the container, a gas charging method using the gas charging apparatus, and a gas discharging method using the gas discharging apparatus.
2. Description of the Related Art
In the fabrication of semiconductor devices, a carrier cassette for storing a plurality of semiconductor wafers is used to transport the wafers between fabrication units. As an example of the carrier cassette, there is a closed container called a FOUP (Front Opening Unified Pod) configured to be filled with an inert gas for the purpose of preventing the oxidation of the surface of each wafer.
Japanese Patent Laid-open No. 2009-38074 discloses a technique of charging an inert gas into a container such as FOUP set on a load port. In this technique, the load port is provided with a door and a door opening/closing mechanism for opening and closing the door. When a lid of the container is held by the door and the door is opened by the door opening/closing mechanism, the lid is removed from a body of the container to thereby expose an opening of the body. In this condition, the inert gas is supplied from this opening (see paragraphs [0018], [0020], and [0024] in the specification of the above citation, for example).
In recent years, the following technique has also been adopted to increase the concentration of an inert gas in a container in association with finer wiring patterns. That is, the bottom of the container is provided with a charge valve (charging hole) for charging the inert gas into the container, and a nozzle for charging the inert gas is provided to charge the inert gas through the charge valve into the container.